Telephone system.



11. s. HULPISH.

f TELEPHONE SYSTEM.

APPLIOATIONIILED NOV. 26, 1910. BENEWED DEO. 22, 1913.

11 1 2, 1 40. Patented sept. 29, 1914.

1 INVENTORZ lll: NOUN/5 min-.Rb 1.0., iJHOm-LIIHCMl WASHINGTON, u4 r.

UNITED sTATEsr PATENT oEEIcE.

DAvID s. IIULEISH, OE TORONTO, ONTARIO,` CANADA, AssIGNOR To CANADIANINDEPENDENT TELEPHONE COMPANY,I.IMITED, OE TORONTO, CANADA, A

cORPORATION OF CANADA.

TELEPHONE SYSTEM.

Specication of Letters Patent.

PatentedSept. 29, 1914.

Application led November 26, 1910, Serial No. 594,257. Renewed December22, 1913. Serial No. 808,274.

T0 all whom 'it may concern Be it known that I, DAVID S. HULFISH, a

citizen of the United States of America, and a resident of Toronto,Province of Ontario, and Dominion of Canada, have invented a new anduseful Improvement in Telephone Systems, of which the following is aspeci-` fication.

My invention pertains to telephone systems and switching devices and hasspecifically as its object the provision of switching devices suitablefor giving service to tele-` phone lines upon each of which is connectedmore than one telephone station.

By my invention I provide a systenr wherein the operations atthevcentral oiiice are in no way different with a reverting call,

namely, when one station upon a imulti party line calls for anotherstation upon the same line, ascompared with a call for a` station uponany other line of the exchange system.

I accomplish this result by removing the test condition from theanswering connective device while applyingthe test upon the` called linewith the calling connective device, and by this means permit the callingdevice to connect with the line because the busy test is not receivedfrom the line. I-Iaving thus connected with the required lineindependently of the fact that it may:

or may not be the line originating the call, I provide means for ringingthe required station upon the line by the operation of the switchboardringing key `and without requiring the calling station to hang upthereceiver. The operation under the principles of my invention is the samewhether the call is reverting or not, although the action of thesupervisory signals of a manual switchboard may be such as to enable theoperator to distinguish between the two classes of calls, if for anyreason such discrimination should be deemed an advantage.

This specification is accompanied by four figures of drawings of whichFigure 1 shows a complete telephone line, a complete connective deviceembodying the principles of my invention and the busy test elements ofanother telephone line; Fig. 2 shows the sub-station equipment of analternative form of signaling and circuits for multiparty lines; Fig. 3shows generators and ringing keys adapted to cooperate with vthe iequipment of Fig. 2; and Fig. 4 shows a ing jacks 4 4 have their longsprings connected to conductorl. The connecting plug paireXtends fromanswering plug 9 to calling plug 10. Talking battery 11 is connectingsprings as is usual with ringingkeys and has also two pairs of springsnormally closed which, when the ringing key is operated to ring, act toopen the circuit of both sides of the talking pair between the plug 9`and the repeating coil 12, thus isolating the conductors of the callingline from the repeatlng coil bridge. The listening key 14 has onenormally closed contact through kwhich the tip of the plug 10 isconnected to .the repeating coil 12. When the listening key is operatedto connect the telephone 15, the telephone is connected to the outersprings 16, 17, of the key, the spring `18 is `broken from` the spring16 and makes contact withfthe` spring 19. This connects the tip of theplug 10 while the Operator is listening in through the circuit 20, 13,21, 18, 19, 22 and helix of relay 23 to earth. The telephone 15 has nopermanent connection to the tip of testing plug 10 whereby any audibletest might be received directly. The ordinary action of testing is asfollows, assuming that the `test conductor 24 of a desired line isconnected to the main battery 11 by reason of the insertion therein of aconnecting plug 10 When the tip of the plug 10 touches the test ring 24"of the desired line, current flows from earth through battery 11 plug10 conductor 24, test ring 24', tip of plug 10, conductor 20, key 13,con- "ductor 21,springs 18, 19, conductor 22 and helix of 28 to earthenergizing relay 23. "By the operation of the armature of relay Aedthrough the split repeating coil 12. The l ringing `keylis provided withsiX switchy23, the body of plug 9 is disconnected from main battery 11`and the conductor 25 is connected to the conductor 22 subsequently. Thispermits a current from the conductor 22 through the conductor 25, andone corner of coil 12 to earth; this current produces an audible signalinthe receiver 15. In the case of fa -reverting call, fthe conditie-n isthat of plug 1() attempting the test upon a test ring which is busy byreason of its opnnection with plug 9. This is indicated by the dottedline 26. lvl/'lien the tip of v10 touches the test ring 'of 3, currentflows through ii, 27, es, 29, 3o, si, 9, s, s', i0, 20,'13',21, 13, 19,22 and heliX of 23, energizing 23. The relayl 23 has its core charged bycurreiitreceived through its own back contact g. it actstherefore asabuzzer incase the it is imposible for a circuit ever to be closed whichwill includethe batteryll in series `'with conductors 30- and 25 sinceconductor 30 isremoved from conductor 22 before conductor25 isappli-ed,v to conductor 22 and thus the test-responsive device, namely,the

vwhen testing'the jack-3, will insert the plug 10 inthat jack, and ofcourse, without removing her plug 9 from jack'S. Her neXt action is toring. Assuming that station 4 lhas called for station 3, Vthe action ofthe ringing key 13 is -to apply the earth of spring 33 throughconductor20 and the short spring O'jaCkBto conductor 1, and also toapplythe generator 35 of the spring 34 to plug 10v through conductor 36, andthence through the long springof jack 3, to the conductor 2 whencecurrent will flow through the ringer 'of station 3 to earth and throughthe telephone bridge of station '4 which is closed by its acty ofcalling and-to conductor 1 andl to earththrough spring 33. Vhile theringing condition has been existing, the ringing key 13 by its fourmiddle springs has separated conductor 37 from conductor 38 andconductor 39 from conductor 40, thereby preventing a short-cir cuitingofy the line by the low resistance oi' .the repeating coil y12 andpreventing a waste of ringing current from theI calling plug through theanswering plug.

To avoid the objectionable feature of the current How from the ringinggenerator through ,the vtalking bridge of the calling ktelephonestation,/I prefer a signaling circuitlas 'illustrated on Figs. 2 and 3.In. this `case harmonic or tuned ringers are suitable.;

At stations 41 and 43, the ringers are con-i ynected from wire 2 toearth and at stations 42 and -44 the ringers are connected `from wirelto earth. kThe connections of ringing Hthe telephone bridge of the lineany current other than a very small current due to any unbalanced detailof the line.

In'Fig. 2 the conductors 1 and 2 are the.

conductors numbered similarly in Fig. 1 and `in Fig. 3 the terminals 3334 are the terminals of the ringing key springs 33 and 34.

In Fig. 4, a inodiication is shown. Resist'- ances 45, 46, are connectedbetween conductors 37 and 38 and between conductors 39 and v40. Theseresistances are su'lliciently high to enable ringing over the telephoneline tobe accomplished, and the action of 'key 13 does not increase theresistance of the lanswering plug beyond the limit set by the resistance45 and 46. Without the resistance 45 and 46, the action of the key 13 byits middle springs isto raise the resistance of the `conductors of theplug 9 to a very high value by opening all nominally conductiveconnections.

It is obvious that many modiiications not specilically shown may be madewithout departing from the spirit or scope of my invention. If theresistance between plug 9 vand repeating coil 12be suiliciently highwhen measured along the paths to earth, then it becomes unnecessary forkey 13 to increase that resistance still farther to obtain successfulringing. I have shown a switchboard system of a well-known typeinodilied to embodyiny invention; switchboard systems of other typesobviously may be modiiied but the requirements would be different indetail.

In the specific application of my invention herein illustrated, thesignal lamp 47 will be extinguished as soon as the operator inserts theplug 10 in the jack 3 by reason of the bridge of the calling station 4across the conductors 1 and 2. This will indicate to the operator thatthe call is a reverting one. Furthermore, when the ringing key 13 isoperated, both of the lamps 47 and 29 will be illuminated since theringing key breaks the conductors of both plugs and causes the releaseof both supervisory relays. This will be au additional indication to theoperator that the call is a reverting one. The operation of theswitchboard for the completion and supervision of the call does notdiffer by reason of these indications. While the operator is listeningupon a completed connection not reverting, current for lel paths fromplug 10 through helix of 23 to earth and through one corner of repeatingcoil 12 in serieswith the armature and contact of test relay 23.

Relay 48 is energized and connects conductor 30 to plug 9 during theperiod when plug 10 is inserted in any jack, hence `after plug 10 isinserted the energization of relay 23 by the listening of the operatorwill not remove the test connection from the body of plug 9.

Having thus described my invention, what I claim as new and desire tosecure by United States Letters Patent is:

1. In a telephone syst-em, a telephone line; a plurality of central oicejacks for said telephone line; a connecting plug-pair comprising in parta calling plug and answering plug and a test relay; a main battery; acircuit from said battery through an armature contact of said relay tothe body of said answering plug; a circuit from the tip of said callingplug to and through the helix of said test relay; and an auxiliary testcircuit from a contact of said relay, said relayy being adapted to actwhen energized, first, to open the connection between said battery andsaid answering plug, and second and subsequently to close circuitbetween said auxiliary test circuit and said calling plug, substantiallyas described. v

2. In a telephone system, answering and calling plugs; answering andcalling jacks; a busy test relay; a test circuit extending from thecalling plug to the test relay and controlling the relay; an auxiliarytest cir cuit extending from the relay to the operators telephone andcontrolled by the relay; and contacts on said relay adapted to removethe busy test conditions from the answering plug and ack when a busytest condition is encountered upon a tested line by the calling plug,substantially as described.

3. In a telephone system, a connective plug pair having two switchingplugs and adapted to connect with the same line at the same time withboth its switching plugs; a battery; and a ringing key forming a part ofsaid connective plug pair and adapted to disconnect the battery from thecalling line at one of its plugs and to connect a ringing generator tothe line at the other of its switching plugs substantially as described.

l.. In a telephone system, a callanswering plug, a ringing plug and aringing key having contacts opening the talking conductors between thecall-answering plug and its associated plug-pair apparatus while ringingupon the ringing plug.

5. In a telephone system, a testrelay; a main test circuit through saidrelay and an auxiliary test circuit from said relay to the test vrelayin each pair associated with the body of the answering plug and the tipof vthe calling plug and operating vto remove vall test potential fromthe answering plug body when a test current is received from the callingplug tip.

7. In a telephone system a `plurality of pairs of connecting plugs; atest circuit extending when completed through the body of one plug andthe tip of another; and a test relay in each pair associated with thebody of'theanswering plugandthe tip of the calling plug and operating to`remove all test potential from the answering plug body when a test`current is received from the calling plug tipand a contact upon saidtest relay and connecting the operators telephone to the tip of thecallingplug after the removalof the test potential from the body of theanswering plug.

8. In a telephone system, a testing plug and a relay completing acircuit between said vtesting' plug and the operators telephone;

and a contact on said relay breaking the test conductor of the answeringplug prior to completing the connection from the operators telephone tothe testing plug.

9. In a telephone system, a telephone line; a connective deviceconnecting with both limbs of said telephone line at each of two pairsof'points, and means breaking the connections to the said line at bothpairs of points when ringing at one of said pairs of points. 1

l0. In a telephone system a plug pair comprising with other apparatus `aringing key cutting the talking conductors of both answering and callingplugs from all plugpair apparatus when ringing upon the calling plug. n

l1.k In a telephone system a plug pair connecting` a source of constantcurrent with its two plugs; a generator' `of ringing currents; and meansfor disconnecting both plugs from said source and connecting one plugwith said generato-r of ringing currents.

DAVID S. HULFISH.

Witnesses:

H. M. Rown, F. D. MACKAY.

Copies of this patent may be obtained for ve centsieach, byfaddressngthe Commissioner of Patents,

p Washington, I). C.

